I can tell you this. That if you look at the growth rates, we don't divide out each one but if you look at year-over-year growth rates and so this would be comparing the 5C to last year. It would be comparing the 4S, which was in the mid-tier. The growth in that sector was the highest growth during the quarter we just finished.

In other words, iPhone 5c sales growth from the iPhone 4s during the same quarter a year-ago outpaced the growth Apple saw from last year's iPhone 5 to the iPhone 5s.

"And so we are extremely happy with how it performed last quarter," Cook added.

Of course, statistical growth in and of itself doesn't tell the entire story.

For instance, it's extremely plausible that iPhone 4s sales during Apple's 2013 Q3 were much lower than anticipated, paving the way for even modest iPhone 5c sales to result in tremendous mid-tier growth.

Nonetheless, the news is particularly interesting in light of the fact that many were quick to label the iPhone 5c a flop. Largely overshadowed by the flagship iPhone 5s, the iPhone 5c didn't get off the ground as impressively as some analysts were expecting. Indeed, even Tim Cook at one point noted that the percentage of folks interested in the 5s as opposed to the 5c was higher than Apple had anticipated. iPhone 5c demand, Cook intimated, "turned out to be different than we thought."

But in recent months, the iPhone 5c has seemingly found its footing. Apple continues to advertise the device heavily in large cities, and it even outsold Samsung's flagship Galaxy S5 in Great Britain this past May.

Sales figures aside, the genius behind the iPhone 5c is that it's really nothing more than a re-purposed iPhone 5. But slap a new name on it and provide users some color options and all of a sudden you're not buying an older-generation product, but rather a new device that's just a step below Apple's flagship iPhone 5s. It's a clever bit of product marketing.